The present invention discloses techniques and architecture to implement a high-speed wireless local loop network using a microwave/millimeter wave wireless radio link between a user and a gateway which, in turn, is connected to a broadband backbone network.
In the data transfer industry, the demand for greater bandwidth has created a bottleneck in user access and in approximately the first and/or last mile of the network. The 1996 FCC release of the spectrum in the 27 to 31 GHz band for Local to Multipoint Distribution Services (LMDS), and the availability of the 5 GHz U-NII band are accelerating the development of wireless broadband network solutions. Traditionally, LMDS and Multi-channel Multipoint Distribution Services (MMDS) have been used to deliver video programs for education and entertainment in an analog format, with broadcast radii of one to five miles, and ten to forty miles, respectively. With the increasing acceptance of digital video and video compression methods alongside the increased system capacity, the need for two-way high-bandwidth transmissions in digital form is gaining importance. The current digital LMDS system, with its large usable bandwidth at mm-wave frequencies, is capable of offering high-speed data transmission rates of up to several Gbps, a sufficient transfer rate to support applications such as high-speed Internet, interactive video, video conferencing, while simultaneously including many other traditional broadcast and digital television channels. The LMDS and MMDS services operate in a cellular fashion, transmitting information between a central hub and fixed subscriber units, which are installed at businesses and homes, using highly directional antennas.
Although the transmission-rate related benefits of the current LMDS and MMDS architectures can be readily seen, the conventional LMDS and MMDS system concepts and architectures were originally designed for one-way distribution, and are not optimized for two-way broadband applications to home and small business users concentrated in highly populated regions such as city and downtown areas. Additionally, the current LMDS architecture suffers heavily from difficulties in installation and alignment, high radiation power to broadcast over a wide coverage radius, and losses due to multipathing, obstructions, excessive environment-related signal attenuation, and adjacent cell interference. Extensive literature exists regarding LMDS and MMDS system technology concerning both theoretical and device-specific aspects as surveyed, for e.g., by:
D. Gray, xe2x80x9cA Broadband Wireless Access System at 28 GHzxe2x80x9d, 1997 Wireless Communications Conference, IEEE, pp. 1-7.
H. Graves, xe2x80x9cA Detailed Analysis of MMDS and LMDSxe2x80x9d Feb. 23-26, 1997 IEEE MTT-S Symposium, Vancouver, B. C., Canada, on Technologies for Wireless Applications Digest, pp. 7-10.
H. Izadpanah, D. Gregoire, J. Schaffner, and H. P. Hsu, xe2x80x9cMM-Wave Wireless Access Technology For The Wideband Wireless Local Loop Applicationsxe2x80x9d, 1998 IEEE Radio and Wireless Conference (RAWCON""98) Colorado Springs, Colo., August, 1998.
H. Izadpanah, xe2x80x9cLMDS: A Broadband Wireless Access Technology: An Overviewxe2x80x9d, The 3rd IAA Annual Conference on xe2x80x9cComputers and Communicationsxe2x80x9d, The City University of New York, N.Y., September 1998.
Birendra Dutt and James K. Chan, xe2x80x9cEquipment for the LMDS Bandxe2x80x9d, 3rd Annual Wireless Communications Conference Digest, WCC ""98, San Diego, Calif. 1998, pp. 47-51.
J. Schaffner, H. Izadpanah, and H. P. Hsu, xe2x80x9cMillimeter Wave Wireless Technology and Testbed Development for Wideband Infrastructure Accessxe2x80x9d, WCC ""98, San Diego, Calif., November 1998.
In contrast, the present invention is intended to provide a two-way broadband data transfer method and to overcome the transmission difficulties associated with the conventional MMDS and LMDS technologies.
In accordance with the present invention, architectures and network implementation techniques for a wideband wireless access local loop using millimeter wave band technology provide a high-speed data transfer link between customer interface equipment and access interface equipment. This link serves as a gateway to a network including processing nodes interconnected by a high-transmission rate medium such as fiber optic cable. System operation is based on the use of millimeter wave transceiver/antenna positioned in a close proximity of up to a few hundred meters to allow for the wireless transfer of data to and from local structures without the logistical and financial difficulties associated with rain attenuation, object blockage, multipath dispersion, and high broadcast power requirements.